In recent years, several studies have built upon the landmark 1987 Lovaas study on the UCLA model of early intervention, replicating and extending research on the efficacy of ABA. In Lovaas' seminal study, it was reported that 47% of children with Autism who received approximately 40 hours per week of ABA initiated prior to the age of 4 achieved normal intellectual and education functioning, with normal-range IQ scores and successful first grade performance in public schools. Similar findings have been extended to children receiving services in a workshop model (Sallows & Graupner, 2005) and from private (non university-based) clinics (Cohen et al., 2006). Further, intensive ABA (25-40 hours per week) was shown to outperform similarly intensive levels of "eclectic" treatment across all developmental domains with the exception of motor skills (Howard et al., 2005). In sum, the body of evidence supporting the efficacy of ABA continues to grow.

The behavioral / ABA treatment was designed to progress gradually and systematically from relatively simple tasks, such as responding to basic requests made by an adult, verbal and nonverbal imitation, labeling objects, actions, and abstract concepts such as colors, size, and prepositions. The treatment progressed further to more advanced programs such as answering questions, conversation and making friends with peers. The program also emphasized play and social skills, progressing from simple toy play and parallel play, to more advanced skills such as symbolic play and cooperative play. Instruction was based on the principals of learning, initially took place in a one-to-one discrete trial format, and later shifted to more naturalistic teaching strategies to focus on generalization. The eclectic treatment was designed to reflect commonly used interventions often described as "best practices" for children with Autism, including using elements from a variety of different teaching procedures, behavioral procedures, and sensorymotor therapies, as well as methods derived from personal experience. Discrete trial training was not utilized.